The Advertising Standards Authority has revealed that it has issued hundreds of warnings against social media influencers for breaking paid partnership rules in the past year.
"Between 200 and 300" social media influencers have been warned by the advertising watchdog, according to Sky News.
The ASA told Campaign that this number was an estimate based on work it has undertaken in the past 12 months to make influencers aware of UK rules around social media advertising.
The watchdog added that it is difficult to provide an exact figure of how many influencers have been contacted formally or informally, because influencers are not a distinct category on its database.
Influencers and celebrities are supposed to distinguish paid-for messages by writing #ad under a post or using "paid partnership" tools on online platforms such as Instagram.
A poll of 2,000 people in the UK last year found that nearly three-quarters think the ASA should do more to enforce paid-for disclosures, while 56% said brands and influencers should be punished for not disclosing commercial relationships.
A month later, the ASA began a project to examine if people browsing online are able to recognise online ads as advertising, including by how they are labelled.